The present invention relates to a program and verify method of a nonvolatile memory device.
In recent years, there has been an increasing demand for nonvolatile memory devices which can be electrically programmed and erased and do not need the refresh function of rewriting data at specific intervals.
A nonvolatile memory device generally includes a memory cell array in which cells for storing data therein are arranged in matrix form, and a page buffer for writing memory into specific cells of the memory cell array or reading memory stored in a specific cell. The page buffer includes a bit line pair connected to a specific memory cell, a register for temporarily storing data to be written into a memory cell array, or reading data of a specific cell from the memory cell array and temporarily storing the read data therein, a sense node for sensing the voltage level of a specific bit line or a specific register, and a bit line selection unit for controlling whether or not to connect a specific bit line to the sense node.
In a program operation of this nonvolatile memory device, a verify operation for determining whether programming has been completed is also performed. That is, a program voltage and a verify voltage are applied sequentially, and this operation is performed repeatedly until the program operation is completed. The program voltage and the verify voltage are applied in such a manner that an output voltage of the block selector is precharged and therefore voltage applied to a global word line is transferred to a local word line. However, the conventional method includes an operation for precharging the output voltage of the block selector whenever the program voltage and the verify voltage are applied. Consequently, a problem arises because an overall program time and verification time increases.